Scientists team up to stop fist-sized snails' spread

Friday

May 10, 2013 at 11:02 AM

As the weather warms, an aquatic invader is revealing itself in the bayous and ditches of Terrebonne and Lafourche parishes.

Nikki BuskeyStaff Writer

As the weather warms, an aquatic invader is revealing itself in the bayous and ditches of Terrebonne and Lafourche parishes.Invasive apple snails have gained a local foothold since their appearance in Donner five years ago, and scientists at Nicholls State University and the Barataria-Terrebonne National Estuary program are planning a possible partnership to monitor the critters and test ways to control their spread.Apple snails are fist-sized mollusks from South America popular in the aquarium trade thanks to their large, beautiful shells. Dumped by disinterested owners into area bayous, the snails are now a common sight in Bayou Black, Donner, Gibson, Bayou Terrebonne and many smaller connected waterways between.The most obvious sign of an apple snail infestation is their eggs, which are a bright bubble-gum pink and appear just above the waterline during warmer months. The snails can lay hundreds of tiny eggs in one bunch. They'll continue to lay eggs as long as the weather is warm, which means they could produce from spring to fall. They do have some local predators, including raccoons, otters and wading birds. But they reproduce so rapidly that predators can't keep up, said Michael Massimi, invasive species coordinator with the Barataria-Terrebonne National Estuary Program. Gary LaFleur, an associate biology professor at Nicholls State University, said he's planning a project with the Estuary Program that would track the snails' spread in local waterways, investigate what they're eating and test some possible control measures. If approved, scientists hope to begin that work in October.“One thing we want to do is be on top of what's going to happen if they get too close” to the Gulf Intracoastal Waterway, LaFleur said. The Intracoastal serves as a highway for invasive species, giving them a route to the rest of the Gulf Coast. LaFleur said it's possible that the saltwater levels in the Intracoastal may be keeping the snails at bay, though the stretch through Houma is mostly fresh water.The snails are poised to enter Bayou Lafourche, something scientists are also trying to prevent, LaFleur said.The snails are extremely hard to get rid of once they do populate an area, Massimi said. The best thing you can do to combat the snails is crush their eggs or collect and kill the individual snails. Both methods are labor intensive.LaFleur said he hopes to look into other methods of controlling apple snails, including using baited traps, which have proved effective. There are some chemicals that kill apple snails, but they can also take out native species, making that a less attractive option, LaFleur said.Apple snails are relatively new to the system, and scientists can only speculate on the impact they'll have. “No one likes an invader, but it's not obvious yet what the impacts will be,” LaFleur said.But Massimi did say people have noticed fewer plants in areas where apple snails are common. That too can be a problem because the lack of plant life could allow algae to take over, and it would mean less food and cover for native species.LaFleur said he hoped the snails might make themselves useful by feeding on some of the invasive plants, like hydrilla, that clog area bayous. But so far they haven't made a dent.The snails have also invaded parts of Florida, Texas and southeast Asia, where they've caused significant rice-crop damage. LaFleur said a big worry is that apple snails could spread to rice crops in western Louisiana and cause serious damage.A question often asked about the invasive snails is whether they're edible. Many locals have said that if the apple snail can be integrated into Cajun cooking, the problem would take care of itself.Nicholls biologists have investigated that possibility, LaFleur said.The snails shouldn't be eaten raw because of concerns about parasites or bacteria, LaFleur said. If cleaned well and cooked thoroughly, the snails can be used in traditional Cajun dishes.“There have been some attempts to cook them into a gumbo,” he confirmed. “If you can make a good gumbo, you can add apple snails, and it won't mess it up.”

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